package com.ruoyi.common.utils;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5Util {

	/**  
	 * 默认的密码字符串组合，用来将字节转换成 16 进制表示的字符,apache校验下载的文件的正确性用的就是默认的这个组合  
	 */    
	protected static char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6','7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };    
	protected static MessageDigest messagedigest = null;    
	static {    
		try {    
			messagedigest = MessageDigest.getInstance("MD5");    
		} catch (NoSuchAlgorithmException e) {    
			e.printStackTrace();    
		}    
	}    
	/**
	 * 获取文件MD5值
	 * @param file
	 * @return
	 * @throws IOException
	 * @date   2012-1-9下午3:15:43
	 */
	public static String getFileMD5String(File file) throws IOException {    
		InputStream fis;    
		fis = new FileInputStream(file);    
		byte[] buffer = new byte[1024];    
		int numRead = 0;    
		while ((numRead = fis.read(buffer)) > 0) {    
			messagedigest.update(buffer, 0, numRead);    
		}    
		fis.close();    
		return bufferToHex(messagedigest.digest());    
	}    

	/**
	 * 根据文件路径计算文件的MD5
	 *
	 * @param fileName
	 * @return
	 * @throws IOException
	 */
	public static String getFileMD5String(String fileName) throws IOException {
		File f = new File(fileName);
		return getFileMD5String(f);
	}


	/**
	 * 密码字符串MD5加密 32位小写
	 * @param str
	 * @return
	 * @date   2012-1-9下午3:16:04
	 */
	public static String getStringMD5(String str){  
		if(StringUtils.isBlank(str)){
			return "";
		}
		byte[] buffer=str.getBytes();  
		messagedigest.update(buffer);  
		return bufferToHex(messagedigest.digest());  
	}  

	public static String bufferToHex(byte bytes[]) {    
		return bufferToHex(bytes, 0, bytes.length);    
	}    

	private static String bufferToHex(byte bytes[], int m, int n) {    
		StringBuffer stringbuffer = new StringBuffer(2 * n);    
		int k = m + n;    
		for (int l = m; l < k; l++) {    
			appendHexPair(bytes[l], stringbuffer);    
		}    
		return stringbuffer.toString();    
	}    

	private static void appendHexPair(byte bt, StringBuffer stringbuffer) {    
		char c0 = hexDigits[(bt & 0xf0) >> 4];// 取字节中高 4 位的数字转换    
		// 为逻辑右移，将符号位一起右移,此处未发现两种符号有何不同    
		char c1 = hexDigits[bt & 0xf];// 取字节中低 4 位的数字转换    
		stringbuffer.append(c0);    
		stringbuffer.append(c1);    
	}

	private static final String toHex(byte hash[]) {
		if (hash == null) {
			return null;
		}
		StringBuffer buf = new StringBuffer(hash.length * 2);
		int i;

		for (i = 0; i < hash.length; i++) {
			if ((hash[i] & 0xff) < 0x10) {
				buf.append("0");
			}
			buf.append(Long.toString(hash[i] & 0xff, 16));
		}
		return buf.toString();
	}

	public static String hash(String s) {
		try {
			return new String(toHex(getStringMD5(s).getBytes("UTF-8")).getBytes("UTF-8"), "UTF-8");
		} catch (Exception e) {
			return s;
		}
	}
	
	/**
	 * 对字节数组进行加密
	 * @param bytes
	 * @return	16位字节数组
	 * @date   2012-1-9下午3:16:04
	 */
	public static byte[] getMD5Byte(byte[] bytes) { 
		messagedigest.update(bytes);   
		return messagedigest.digest();   
	} 
	
	//测试
	public static void main(String[] args) throws Exception {
		System.out.println(MD5Util.getStringMD5("123456"));
		System.out.println(MD5Util.getStringMD5("123456").substring(8, 26).toUpperCase());//21232f297a57a5a743894a0e4a801fc3
		System.out.println(MD5Util.hash("123456"));//21232f297a57a5a743894a0e4a801fc3
		//49BA59ABBE56E057F2

	}
}
